Method and apparatus for forming stretch blow molded containers

Abstract

The present invention relates to a base assembly ( 100 ) for forming a base portion of a plastic container. The base assembly comprises a base pedestal ( 104 ), a base mold attached to the base pedestal, a push rod ( 102 ) movable between a first position and a second position with respect to the base mold to reposition a portion of the plastic container, and an activation mechanism adapted to move the push rod between the first position and the second position.

What is claimed is: 
     
       1. A method of stretch blow molding a plastic container, comprising:
 (a) enclosing a parison within a mold cavity of a blow mold within a stretch blow molding system, the blow mold comprising a side mold assembly and a separate base plug including a base mold defining a contact surface to form a shape of at least a part of a base portion of a plastic container, the contact surface including a cavity, an outer surface and an end surface of a push rod, the cavity being recessed relative to the end surface of the push rod, wherein the push rod extends through the base plug; 
 (b) inflating the parison within the mold cavity to form a blow molded container having a movable region using the method of stretch blow molding; and 
 (c) moving a portion of the blow mold to reposition the movable region while the blow mold container is in the mold cavity by moving the push rod from a first position to a second position so as to reposition the movable region from an outwardly protruding position toward an inwardly protruding position. 
 
     
     
       2. The method of  claim 1 , wherein step (c) further comprises activating an air cylinder to move the push rod from the first position to the second position. 
     
     
       3. The method of  claim 1 , wherein step (c) further comprises engaging a cam follower associated with the push rod with a cam member. 
     
     
       4. The method of  claim 1 , wherein the blow mold comprises a plurality of mold portions including the base mold and the side mold assembly. 
     
     
       5. The method of  claim 1 , wherein step (c) is triggered mechanically. 
     
     
       6. The method of  claim 1 , further comprising (d) releasing the blow molded container from the mold cavity. 
     
     
       7. A method of stretch blow molding a plastic container, comprising:
 (a) enclosing a parison within a mold cavity of a blow mold within a stretch blow molding system defining the mold cavity, the blow mold comprising a side mold assembly and a separate base plug including a base mold defining a contact surface to form a shape of at least a part of a base portion of a plastic container, the contact surface including a cavity, an outer surface and an end surface of a push rod, the cavity being recessed relative to the end surface of the push rod, wherein the push rod extends through the base plug; 
 (b) inflating the parison within the mold cavity to form a blow molded container having a movable region using the method of stretch blow molding; and 
 (c) moving a portion of the blow mold to reposition the movable region while the blow mold container is in the mold cavity by moving the push rod from a first position to a second position so as to reposition the movable region from an outwardly protruding position toward an inwardly protruding position. 
 
     
     
       8. The method of  claim 1 , wherein the side mold assembly comprises a first side mold and a second side mold.